| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame^] | 1 | /* Copyright (C) 1994-2015 Free Software Foundation, Inc. |
| 2 | This file is part of the GNU C Library. |
| 3 | |
| 4 | The GNU C Library is free software; you can redistribute it and/or |
| 5 | modify it under the terms of the GNU Lesser General Public |
| 6 | License as published by the Free Software Foundation; either |
| 7 | version 2.1 of the License, or (at your option) any later version. |
| 8 | |
| 9 | The GNU C Library is distributed in the hope that it will be useful, |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | Lesser General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU Lesser General Public |
| 15 | License along with the GNU C Library; if not, see |
| 16 | <http://www.gnu.org/licenses/>. */ |
| 17 | |
| 18 | #include <sys/types.h> |
| 19 | #include <unistd.h> |
| 20 | #include <fcntl.h> |
| 21 | #include <errno.h> |
| 22 | #include <string.h> |
| 23 | |
| 24 | /* lockf.c defines lockf64 as an alias if __OFF_T_MATCHES_OFF64_T. */ |
| 25 | #ifndef __OFF_T_MATCHES_OFF64_T |
| 26 | |
| 27 | /* lockf is a simplified interface to fcntl's locking facilities. */ |
| 28 | |
| 29 | int |
| 30 | lockf64 (int fd, int cmd, off64_t len64) |
| 31 | { |
| 32 | struct flock fl; |
| 33 | off_t len = (off_t) len64; |
| 34 | |
| 35 | if (len64 != (off64_t) len) |
| 36 | { |
| 37 | /* We can't represent the length. */ |
| 38 | __set_errno (EOVERFLOW); |
| 39 | return -1; |
| 40 | } |
| 41 | |
| 42 | memset ((char *) &fl, '\0', sizeof (fl)); |
| 43 | |
| 44 | /* lockf is always relative to the current file position. */ |
| 45 | fl.l_whence = SEEK_CUR; |
| 46 | fl.l_start = 0; |
| 47 | fl.l_len = len; |
| 48 | |
| 49 | switch (cmd) |
| 50 | { |
| 51 | case F_TEST: |
| 52 | /* Test the lock: return 0 if FD is unlocked or locked by this process; |
| 53 | return -1, set errno to EACCES, if another process holds the lock. */ |
| 54 | fl.l_type = F_RDLCK; |
| 55 | if (__fcntl (fd, F_GETLK, &fl) < 0) |
| 56 | return -1; |
| 57 | if (fl.l_type == F_UNLCK || fl.l_pid == __getpid ()) |
| 58 | return 0; |
| 59 | __set_errno (EACCES); |
| 60 | return -1; |
| 61 | |
| 62 | case F_ULOCK: |
| 63 | fl.l_type = F_UNLCK; |
| 64 | cmd = F_SETLK; |
| 65 | break; |
| 66 | case F_LOCK: |
| 67 | fl.l_type = F_WRLCK; |
| 68 | cmd = F_SETLKW; |
| 69 | break; |
| 70 | case F_TLOCK: |
| 71 | fl.l_type = F_WRLCK; |
| 72 | cmd = F_SETLK; |
| 73 | break; |
| 74 | |
| 75 | default: |
| 76 | __set_errno (EINVAL); |
| 77 | return -1; |
| 78 | } |
| 79 | |
| 80 | return __fcntl (fd, cmd, &fl); |
| 81 | } |
| 82 | |
| 83 | #endif |